Polyphase supply circuit



June 9 9 J. H. ANDRESEN, JR., ETl kL 2,472,507

POLYPHASE SUPPLY CIRCUIT Filed Oct. 19, v194s S mmw 3pm Z M Z 5 T T @MQLUILUIMRE umnwwmw Patented June 7, 1949 POLYPHASE SUPPLY CIRCUIT John H.Andresen, Jr., Port Washington, and Edward Kasner, Brooklyn, N. Y.,assignors to Square D Company, Detroit, Mich, a corporation of MichiganApplication October 19, 1946, Serial No. 704,512

Claims.

This invention relates to an improved form of electronic circuit forproducing a polyphase output from a single phase input and moreparticularly a two-phase output from a single phase input with theoutput frequency and sub-multiple of the input frequency.

The frequency meter herein described is described and claimed in adivisional application.

Other objects and features of the invention will be readily apparent tothose skilled in the art from. the specification and appended drawingsillustrating certain preferred embodiments in which:

Figure 1 is a wiring diagram of an electronic circuit and frequencymeter according to the present invention, in which the frequency of thesingle phase input is divided in the two phase output which feeds asynchronous motor driving a drag cup tachometer indicator.

Figures 2, 3, 4, 5 and 6 are representations of the wave form outputs ofvarious tubes of the circuit of Figure 1.

In the diagram of Figure 1, the single phase input is applied at l and 2and is fed through a protective resistor 3 to the control grid 4 of avoltage amplifying triode 5. The wire 2 is connected to ground andacross I and 2 is provided a grid resistor B. The cathode 'l of thetriode 5 is connected to ground through cathode resistor 8 and by-passcondenser 9. The anode ll of the triode 5 is connected to the supplythrough the load resistor l2.

The supply is provided from an alternating current source to the supplytransformer primary it; having secondary filament windings l4 and I5 anda main winding l6 supplying direct current through the rectifier tube I1and the filter circuit represented by the inductance l8 and condensersIS.

The amplified output of the triode 5 is connected through a couplingcondenser 2| and grid limiting resistor 22 to the control grid 23 of apentode 2 3, the grid resistor being indicated at 25. The pentode 24 andits circuit serve as an amplifier-limiter which not only furtheramplifies the output of triode 5 but produces a square Wave output. Thepentode 24 has a screen grid 2%; connected through by-pass condenser 21to ground and through the voltage dropping resistor 28 to the supply.The suppressor grid 29 of the pentode 2-3 is connected to the cathode 3|and these are connected to ground and through a condenser 32 to thesupply, the condenser 32 and resistor 33 constituting a decouplingfilter to sup- 2 press alternating current on the dividers to-behereinafter described.

The output of the pentode 2 i is fed through coupling condensers i l and35 to the grids 36 and 31 of triodes 3B and 39 formin part of an Eccles-Jordan frequency divider circuit. This circuit includes resistors 40,4!, 42, 43 and resistors 44, 45, it, 41, which resistors form voltagedividing circuits which impress the grid bias on the tubes 38, 59.Condensers 48, 39 parallel the resistors t5 and ii. Anodes 5i and 52 oftubes 38 and 39 are connected to the supply through the resistors at, Mand d2, 43, respectively. The cathodes 53 and 54 are connected to groundthrough cathode resistor 55 and by-pass condenser 55.

The output of tube 39 is fed through coupling condensers 57 and 58 tothe grids of tubes 59, 6| forming with their circuit connections asecond Eccles-Jordan frequency divider circuit similar to thatpreviously described in detail for the circuit embodying the tubes 38and 39. Similarly, the output of tube 38 is fed to a third Eccles-Jordancircuit embodyin the tubes 62 and 63. The outputs of tubes 6! and 53 aresuitably amplified and fed to the frequency responsive meter.

The amplifying circuit is represented by the coupling condensers 64 and65, grid resistors 66 and 61, screen grid resistor 68, screen gridbypass 63, tetrodes H and 12, load resistors 13 and M, cathode resistor15 and cathode by-pass condenser 16. The amplified output of tubes H andi2 is fed through coupling condensers l1 and 18 to the two phasewindings l9 and BI of a synchronous motor 82 driving a permanent magnet83 within a conducting drag cup 84 which carries a pointer 85cooperating with a dial 86. The drag cup and its shaft are provided witha biasing spring, not shown, limitin its displacement.

In the operation of the electronic circuit and of the frequency meter ofwhich it forms a part, the input frequency applied at l and 2 may haveany wave form but the unknown frequency should be periodic. This singlephase input is amplified by the tube 5 and the output fed to theamplifier-limiter tube 24 whose output is further amplified and is inthe form of a rectangular wave as shown in Figure 2, regardless of theinput wave form. The frequency of the output of tubes 38 and 39 isone-half that of the input frequency and is in the form illustrated inFigures 3 and 4, being apart. This frequency division is a well knowncharacteristic of the Eccles-Jordan circuit which tends to drive onetube toward cutoff and the other toward saturation. With the applicationof the square wave form input, sharp pulses are applied to the grids.When a positive pulse appears, the tube in the circuit momentarilyconducting undergoes no change. The non-conducting tube attempts toconduct but is prevented from doing so by the negative bias impressedupon it by the other tube. When a negative pulse appears at the grids,both tubes are momentarily driven to cutoff. The charges existing on thecondensers 48 and 49 now exert control of the circuit and the highercharge across the condenser at the initially conducting tube causes theinitially nonconducting tube to conduct heavy and drive the initiallyconducting tube to cutoff. One input cycle causes one transfer ofconduction to produce the one-half frequency output.

The Eccles-Jordan circuits formed by tubes 59, 6| and 62, 63 furtherdivide the outputs of the tubes 38, 39. The outputs of tubes 59, 6| are180 apart and the outputs of tubes 62 and 63 are 180 apart. However, theoutputs of the tubes 5| and 63 are only 90 apart as is shown by the waveform of Figures 5 and 6, since the initial 180 out. of phase relation ofthe wave forms of Figures 3 and 4 becomes 90 upon the frequencydivision. The output of tubes 6! and 63 is amplified in the circuitincluding the tubes H and 12 and feeds the two phase synchronous motor82 which thus rotates at a synchronous speed of one-quarter the inputfrequency.

The magnetic drag cup tachometer has a direct reading dial. indicationcorresponding to the speed of the motor 82. The permanent magcnt 83' isdriven in synchronism with the motor 82 and sets up eddy currents in thedrag cup motor M producing a shaft torque proportional to the speed ofmagnet rotation. This torque acting against a spring in known mannerproduces a displacement of the drag cup shaft proportional to th torque.The pointer 85 mounted on the shaft indicates on the dial St the inputfrequency, the dial 86 hearing indicia calibrated in cycles per second.

The circuit. according to the present invention, not only provides for atwo phase output from a single phase input but subdivides the inputfrequency to any degree desired since any number of frequency dividersmay be placed in advance of the divider circuit represented by the tubes38, 39 to subdivide the frequency to any desired degree. Hence, therange of the frequency meter is independent of the physical limitationsof the synchronous motor. Thus, a synchronous motor having an accuratefrequency response over a range of to 150 cycles per second may, by afrequency subdivision of four, be utilized to operate a frequency meterindicating from 40 to 600 cycles per second and with further division,the range can be further extended as desired. The use of the two phasesynchronous motor is greatly preferred for its efficiency and goodstarting characteristics.

To secure the proper phase relation for continuous motor rotation in thesame direction, it is desired that the firing order of the last dividersshall be consistent. Variation in the firing order of the dividersfeeding thereto is immaterial since the reversal of both phases does noteffect the direction of rotation. To secure the consistent order offiring in the last two dividers of the circuit, their plate loadresistors are unbalanced so that the sections with the lower loadresistances are always out in first to insure consistency in the firingorder and proper rotation of the motor at all times.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparent to thoseskilled in the art and the invention is tobe given its broadest possibleinterpretation within the terms of the following claims.

What is claimed is:

1. A circuit for producing a two phase output of subdivided frequencyfrom a single phase input comprising a limiter circuit in which saidinput is changed to a single phase of the same frequency: but ofrectangular wave form, a frequency divider circuit fed by the singlephase square wave form voltage and producing a pair of voltages ofone-half the initial frequency displaced 180." in time phase relation, asecond frequency divider to which one of said half frequency voltages isfed, a third frequency divider to which the other of said half frequencyvoltages is fed, said second and third frequency dividers each producinga pair of voltages of onequarter the initial input frequency, and meansfor supplying one only of each of said second and third frequencydivider outputs to produce a two phase voltage spaced in time phaserelation.

2. A circuit. for supplying a two, phase output from a single phasesource. comprising a first frequency divider circuit including a pair ofelectronic tubes fed from said input and having their output voltages ofhalf, the input frequency and spaced 18Q in time phase, a second andthird frequency divider each employing a pair of electronic tubes andfed from the outputs of the tubes of said first frequency divider, theoutputs of the tubes of said second and third frequency divider having afrequency one-quarter that of the input voltage, and a circuit connectedto the output to one of the tubes of each of said second and thirdfrequency dividers to produce a two phase output in said last mentionedcircuit having voltages spaced 90 in time phase relation.

3. A circuit for supplying a two phase output from a single phase sourcecomprising a first frequency divider circuit including a pair ofelectronic tubes fed from said input and having their output voltages ofhalf the input frequency and spaced in time phase, a second and thirdfrequency divider each employing a pair of electronic tubes and fed fromthe outputs of the tubes of said first frequency divider, the outputs ofthe tubes of said second and third frequency divider having a frequencyone-quarter that of the input voltage, a circuit connected to the outputto one of the tubes of each of said second and third frequency dividersto produce a two phase output in said last mentioned circuit havingvoltages spaced 90 in time phase relation, and means for insuring aconsistent order of firing of the tubes in said second and thirdfrequency divider to maintain the proper time phase relation in said twophase output.

4. A circuit for producing a two phase output of subdivided frequencyfrom a single phase input comprising a first electronic tube fed fromsaid input and having its output voltage of the same frequency as theinput but of rectangular wave form, a first Eccles-Jordan frequencydivider circuit fed bysaid rectangular wave form voltage and having itsoutput two voltages of subdivided frequency spaced 180 in time phase, a.pair of Eccles-Jordan frequency divider circuits each fed by one of theoutput voltages of said first Eccle's-Jordan circuit and producingoutput voltages of further subdivided frequency, and a circuit fed bytwo only of the four outputs of said pair of Eccles-Jordan circuits toproduce a two phase output of subdivided frequency spaced 90 in timephase relation.

5. A circuit for producing a two phase output of subdivided frequencyfrom a single phase input comprising a first electronic tube fed fromsaid input and having its output voltage of the same frequency as theinput but of rectangular wave form, a first Eccles-Jordan frequencydivider circuit fed by said rectangular wave form voltage and having itsoutput two voltages of subdivided frequency 180 spaced in time phase, apair of Eccles-Jordan frequency divider circuits each fed by one of theoutput voltages of said first Eccles-Jordan circuit and producing outputvoltages of further subdivided frequency and a circuit fed by two onlyof the four outputs of said JOHN H. ANDRESEN, JR. EDWARD KASNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,029,007 Frankenfield June 11,1912 1,614,202 Lenehan Jan. 11, 1927 1,848,866 Baker Mar. 8, 1932 202,333,502 Wickham Nov. 2, 1943

